Magnetic recording media generally comprise a flexible, non-magnetizable support or substrate having two major surfaces. The substrate may have a magnetizable coating on both major surfaces or sides or on just one side and a non-magnetizable backside coating on the opposite side. The former case is more typical of disk media, and the latter is typical of tapes. The medium, when in the form of a tape, typically travels along a tape path and over a record or read head during use, and is wound upon itself on a hub or reel for storage.
With continuing advances in magnetic recording technology leading to thinner tapes, faster winding speeds and higher recording densities, related performance problems become increasingly likely. For instance, magnetic tape tends to build up static charge during use. If the charge is not dissipated, data loss and errors in recording may result.
A phenomenon known as scattered wind occurs when air becomes trapped beneath the rapidly moving tape. The entrapped air causes layer-to-layer slippage, with the result being poor wound roll formation and possible tape edge damage.
When the magnetic surface of the tape is made extremely smooth to reduce noise in recording, running stability may deteriorate. The smooth surface has a high coefficient of friction, causing the tape to stick to guides and heads when stopping and starting. The accuracy of read/write operations is sacrificed.
Backside coatings can be formulated to improve tape conductivity, opacity, durability, winding and tracking characteristics. For instance, backside coatings can be made intentionally rough in order to reduce friction and air entrapment. Unfortunately, new problems may be introduced with this approach. The roughness can be imprinted on the magnetic surface during storage due to layer-to-layer contact or calendering, thereby compromising the data recording properties of the tape.
A durable backside coating which allows air to escape during winding while maintaining an unembossed, smooth magnetic recording surface is needed.